A method of converting operator inputs into control commands in a computer-controlled interlocking system is known from an article by R. Dachwald and J. Raimer in "Signal+Draht 75" (1983), No. 12, in which the alphanumeric keyboard NstP S800 of Siemens is described on page 221 et seq.
In that method, the route setting commands are entered by means of alphanumeric characters into an input unit in a given syntactic form. Before the entered characters can be converted into target information, they are checked for format errors. This necessitates a so-called syntax analysis, a decoding process which is time-consuming and requires a large amount of storage. Compliance with predefined format rules is indispensable; a change in input format accordingly necessitates an alteration of the greater part of the input software. Computer search methods suitable for use in the present invention are known in other connections (see, for example, "Computer", No. 12 of May 29, 1985, pp. 53 et seq).